1. Field of the Invention
An aspect of the present invention relates to an image forming apparatus, and, more particularly, to an image forming apparatus which corrects a paper jam occurring in a fixing device without difficulty.
2. Description of the Related Art
Generally, an image forming apparatus comprises a paper feeding device, a developing device, a fixing device and a paper ejecting device. If the paper feeding device feeds a sheet of printing paper to the developing device, the developing device applies developer to the sheet of printing paper through a predetermined developing process. The fixing device receives the sheet of printing paper on which the developer is applied, from the developing device and fixes the developer to the sheet of printing paper. Then, the paper ejecting device ejects the sheet of paper on which the image is formed to the outside of the apparatus.
FIG. 1 is a front view of a conventional image forming apparatus. As shown in FIG. 1, the image forming apparatus comprises a fixing device 100. The fixing device 100 comprises a pressing roller 110 and a heating roller 120. The pressing roller 110 and the heating roller 120 rotate against and in opposition to each other to generate a moving path “P” for the sheet of printing paper therebetween. The pressing roller 110 applies pressure to the sheet of printing paper. The heating roller 120 comprises a heating part (not shown) to heat the sheet of printing paper and to fix the toner applied thereon. A roller frame 130 supports the heating roller 120.
The sheet of printing paper, which is pressed and heated, respectively, by the pressing roller 110 and the heating roller 120, passes between the pressing roller 110 and the heating roller 120 and is transformed by the heat of the heating roller 120 to curve around an outer circumferential surface of the heating roller 120.
However, the sheet of printing paper may adhere to the heating roller for too long a time and, therefore, may not be carried to a paper ejecting roller (not shown) properly. As such, the sheet of printing paper may not be discharged normally. Moreover, as the sheet of printing paper moves abnormally around the heating roller 120, once the sheet of printing paper gets between the heating roller 120 and the roller frame 130, the sheet of printing paper may be stuck between the heating roller 120 and the roller frame 130. When this happens, a paper jam occurs.
A separation claw 140 is provided in the fixing device 100 to prevent the sheet of printing paper from being curved and moving toward the heating roller 120. The separation claw 140 is disposed on the outer circumferential surface of the heating roller 120, along which the sheet of printing paper may be adhered to. In this position, the separation claw 140 separates the sheet of printing paper curved by the heat of the heating roller 120 from the heating roller 120, thereby inducing the sheet to move toward a normal moving path “P” thereof and to be supplied to the paper ejecting roller (not shown).
The separation claw 140 is supported by the roller frame 130 to be rotated by a claw hinge 142, which has an axis extending in a similar direction as that of the heating roller 120. A claw spring 144 is disposed between the separation claw 140 and the roller frame 130 to press the separation claw 140 with a predetermined amount of pressure so as to bias the separation claw 140 to adhere to the outer circumferential surface of the heating roller 120. The biased separation claw 140 is therefore prevented from being separated from the heating roller 120.
However, if the pressure of the claw spring 144 is lowered such that a gap is generated between the separation claw 140 and the heating roller 120, the sheet of printing paper transformed by heat may be not separated from the heating roller 120 by the separation claw 140 and may end up being stuck between the separation claw 140 and the heating roller 120. That is, a particular type of paper jam, known as an accordion type of paper jam, may occur.
As the separation claw 140 is adhered to the heating roller 120 with considerable pressure by the pressure exerted by the claw spring 144, the accordion type of paper jam is not easily corrected as compared to a typical type of paper jam. Accordingly, this type of paper jam may cause an inconvenience to a user, and the separation claw 140, the heating roller 120 and other surrounding devices may be damaged while a user corrects the paper jam, thereby raising the overall cost of repairs.